Multistage air pump with adjustable inter-stage mass transfer and inter-stage sorbent cartridge

ABSTRACT

A hand operated reciprocating multistage pump has an upstream stage and a downstream stage, each stage having a compression chamber. A regulating valve controls a mass of compressed air passing from the upstream stage to the downstream stage. By controlling the mass of compressed air passing to the downstream stage, the required force to operate the compression chamber of the downstream stage can be controlled. A sorbent cartridge can be located between the upstream stage and the downstream stage, such that the partially compressed air passes through a sorbent such as a desiccant before being compressed in the compression chamber of the downstream stage.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO A “SEQUENCE LISTING”

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a hand operated pump and more particularly to a multistage hand operated air pump, wherein a mass flow rate between stages of the pump can be selectively controlled to thereby control the required force to actuate the pump to achieve a given output pressure.

2. Description of the Related Art

Simple hand operated reciprocal air pumps, such as bicycle tire pumps, have been available for many years. A cylinder and piston within the pump provide a single-action compression system that draws in ambient air on the up-stroke and compresses the air on the down-stroke. Check valves are employed on the inlet and compressed air outlet of the pump, such that a series of reciprocal stokes can be employed to gradually build up the air pressure at the outlet, which may be connected to a pneumatic tire or a storage tank. The compression ratio of the pump limits the maximum pressure that can be developed, which is approached asymptotically. The maximum compression ratio is dictated by the displacement ratio between the volume of the fully open cylinder on the upstroke and the fully closed cylinder on the down-stroke. More efficient versions of such pumps may be configured to compress air on both the up-stroke and the down-stroke.

However, there are increasing applications which require much higher operating pressure, such as high performance air rifles. Such air rifles rival performance of light caliber firearms, and can yield muzzle velocities approaching 1,200 fps. In order to achieve such velocities, an air reserve tank filled at a remote location by a motor, is coupled to the rifle to transfer high pressure air, in the 2,000 psi to 3,600 psi range.

These high pressures cannot be achieved with a single stage reciprocal pump. While multi-stage pumps can be used to provide these pressure levels, in excess of 2,000 psi, the multistage pumps represent a fixed balance between number of strokes to achieve the necessary pressure and the force that must be applied by the operator.

Further, as the desired level of compression of the outlet air rises, so too does the number of mechanical and operation issues in the design and function of the pump. While a simple bicycle pump can function without lubrication in the presence of dust and moisture, high pressure pumps will develop a number of operational problems, and have a greatly reduced useful life in the same environment. Heat, with the addition of dust, particulates or moisture, greatly challenges the functioning of high pressure pumps. Design factors quickly become critical as the desired outlet pressure increases. Such design problems can be partially overcome using higher quality materials, higher performance lubricants, and tighter design specifications, however, such refinements come at increased production costs.

Thus, a need exists for a high pressure, multiple-stage, hand operated reciprocal air pump that can achieve high pressure, have an adequately long useful life, yet be operated by a variety of operators so as to be desirable to consumers.

The specific need exists for a high pressure, multiple-stage, hand operated reciprocal air pump that can achieve high pressure while accommodating the available force that can be applied by different operators. That is, there is a need for such pump that can allow the operator to continuously set the balance between number of strokes and required operating force during operation of the pump to reach a desired outlet pressure.

A need also exits for a high pressure, multiple-stage, hand operated reciprocal air pump that can provide for the conditioning of the compressed air to enhance the useful life of the pump.

BRIEF SUMMARY OF THE INVENTION

The present system contemplates a multistage air pump having an upstream stage having a first compression chamber pressurizing a volume of a gas to a pressure above ambient pressure; a downstream stage having a second compression chamber fluidly connected to the first compression chamber; and a regulating valve selectively venting a portion of the pressurized gas to reduce a mass of pressurized gas passing to the second compression chamber.

In one configuration, the second compression chamber is partly defined by a downstream stage inlet, and the downstream stage inlet includes an inlet valve, wherein the downstream stage inlet is formed by the inlet valve.

The regulating valve is configured to preclude ambient air from passing through the regulating valve into the first compression chamber, while being moveable between a closed position precluding pressurized gas from passing from the first compression chamber to an ambient pressure and an opening position permitting at least a portion of pressurized gas to pass from the first compression chamber to ambient pressure. It is contemplated the regulating valve can be fluidly connected to the second compression chamber.

The multistage air pump can include a transfer tube intermediate the upstream stage and the downstream stage, wherein a sorbent cartridge is located in the transfer tube. Thus, a multistage air pump is provided having a sorbent cartridge fluidly intermediate the upstream stage and the downstream stage.

In an alternative construction, a multistage air pump includes an upstream stage having an upstream stage inlet and an upstream stage outlet, the upstream stage increasing a pressure of a gas from the upstream stage inlet to the upstream stage outlet; a downstream stage having a downstream stage inlet fluidly connected to the upstream stage outlet and a downstream stage outlet; and a regulating valve in fluid communication with at least one of the upstream stage outlet and the downstream stage inlet, the regulating valve selectively passing pressurized gas prior to the downstream stage inlet to decrease a mass of pressurized gas passing through the downstream stage inlet.

In this configuration, the regulating valve decreases a volume of pressurized gas passing through the downstream stage inlet. The regulating valve decreases a mass of pressurized gas passing through the downstream stage inlet.

A method of operating a multistage air pump is provided including increasing a gas pressure in a first compression chamber of an upstream stage to a first pressure; and selectively venting a portion of the pressurized gas prior to entering a second compression chamber in a downstream stage, the venting reducing a mass of pressurized gas transferred from the first compression chamber to the second compression chamber.

The method includes venting during each stroke of the pump, as well as venting through a regulating valve fluidly connected to the first compression chamber. The method also includes venting gas from the first compression chamber.

In a further configuration, a multistage air pump includes an upstream stage having an upstream stage piston assembly and a first compression chamber; a downstream stage fluidly connected to the upstream compression chamber, the downstream stage having a downstream stage piston assembly and a second compression chamber; a handle operably connected to the upstream stage piston assembly and the downstream stage piston assembly; and a sorbent cartridge fluidly intermediate the upstream stage and the downstream stage.

The multistage air pump locates the sorbent cartridge to pass pressurized gas from the upstream compression chamber to the downstream compression chamber through the sorbent cartridge.

The multistage air pump can further include a regulating valve selectively venting a portion of pressurized gas from the first compression chamber to reduce a mass of pressurized gas passing to the second compression chamber. In addition, the multistage air pump can include a transfer tube fluidly intermediate the upstream stage and the downstream stage, wherein the transfer tube is sized to retain the sorbent cartridge.

The present system further provides for a sorbent cartridge for a multistage air pump, the sorbent cartridge having an elongate cartridge tube having an upstream end and a downstream end; an upstream filter within the cartridge tube; a downstream upstream filter within the cartridge tube, the downstream filter spaced from the upstream filter; a sorbent material retained within the cartridge tube intermediate the upstream filter and the downstream filter; an upstream sealing plug at the upstream end of the cartridge tube, the upstream sealing plug having a first circumferential seal and a spaced apart second circumferential seal, the upstream sealing plug including a first through passage extending from a first opening intermediate the first circumferential seal and the second circumferential seal to a second opening within a diameter of the cartridge tube; and a downstream sealing plug at the downstream end of the cartridge tube, the downstream sealing plug having a third circumferential seal and a spaced apart fourth circumferential seal, the downstream sealing plug including through second passage extending from a third opening intermediate the third circumferential seal and the fourth circumferential seal to a fourth opening within a diameter of the cartridge tube.

It is contemplated the sealing plugs can be affixed to the cartridge tube. Further, the sealing plugs can be formed of the same material as the cartridge tube. Alternatively, the sealing plugs can be a different material than the cartridge tube.

In the sorbent cartridge, the upstream filter can be one of a metallic filter or a composite non-woven material.

In certain configurations, the upstream filter is a metallic filter and the sorbent cartridge includes a second upstream filter, wherein the second upstream filter is a composite non-woven material.

Further, the downstream filter can be one of a metallic filter and a composite non-woven material. In other configurations, the downstream filter is a metallic filter and the sorbent cartridge includes a second downstream filter, wherein the second downstream filter is a composite non-woven material.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a right side perspective view of the air pump.

FIG. 2 is a left side perspective view of the air pump.

FIG. 3 is a side elevation cross sectional view of the air pump.

FIG. 4 is a side elevation cross sectional view of a lower end of the air pump.

FIG. 5 is a side elevation cross sectional view of an upper end of the air pump.

FIG. 6 is a perspective view of a sorbent cartridge for location between stages in the air pump.

FIG. 7 is a perspective view of an end of the sorbent cartridge of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a multistage air pump 10 is shown. Generally, the pump 10 includes an upstream stage 20, a downstream stage 120, a regulating valve 240 and a handle assembly 270 for manually actuating the upstream stage and the downstream stage.

Referring to FIGS. 3-5, the upstream stage 20 includes an upstream stage compression tube 30, an upstream stage inlet 32, an upstream stage outlet 36 and an upstream stage piston assembly 40.

The upstream stage compression tube 30 is fluidly connected to the upstream stage inlet 32 and the upstream stage outlet 36. The upstream stage piston assembly 40 is moveable within the upstream stage compression tube 30 in response to movement of the handle assembly 270.

The upstream stage piston assembly 40 includes a piston 50 and a piston rod 60 connecting the piston to the handle assembly 270. The piston 50 divides the upstream stage compression tube 30 into an accumulating chamber 70 between the upstream stage inlet 32 and the piston, and a first compression chamber 90 between the piston and the upstream stage outlet 36. In at least one configuration, the upstream stage outlet 36 is at the location that is not swept by the piston 50.

The piston 50 is moveable between a first position and a second position. In the first position, the piston 50 is located to minimize the volume of the accumulating chamber 70 and maximize the volume of the first compression chamber 90, such as being located adjacent the upstream stage inlet 32, as seen in FIGS. 3 and 4. In the second position, the piston 50 is located to maximize the volume of the accumulating chamber 70 and minimize the volume of the first compression chamber 90, such as adjacent the upstream stage outlet 36. Therefore, as the piston 50 moves between the first position and the second position, the accumulating chamber 70 and the first compression chamber 90 vary in size in an inverse proportion.

The piston 50 includes a bypass seal 52 for passing air from the accumulating chamber 70 to the first compression chamber 90 during a down stroke of the piston, in FIGS. 1-4, (decreasing the volume of the accumulating chamber and increasing the volume of the first compression chamber) and for precluding air passing between the first compression chamber and the accumulating chamber during the upstroke of the piston, in FIGS. 1-4 (increasing the volume of the accumulating chamber and decreasing the volume of the first compression chamber).

While a variety of bypass seals 52 are well known and can be employed, in one configuration, the bypass seal 52 is formed by an annular groove 55 in the piston 50, wherein a bypass duct 57 extends between an upper portion of the annular groove and an upper surface of the piston exposed to the first compression chamber 90. A seal such as an O-ring seal 58 is disposed within the annular groove 55, wherein the annular groove has a greater axial dimension than the seal. Thus, the seal 58 can translate axially while maintaining a sealed interface with an inside surface of the upstream stage compression tube 30. The axial translation of the seal 58 relative to the annular groove 55 and hence bypass duct 57 allows air to pass through piston 50 when decreasing the volume of the accumulating chamber 70 (down stroke of the piston) and precludes passage of air through the piston when decreasing the volume of the first compression chamber 90 (upstroke of the piston).

The upstream stage 20 is fluidly connected to the downstream stage 120. In one configuration, the upstream stage 20 is directly connected to the downstream stage 120. Alternatively, the upstream stage 20 is fluidly connected to the downstream stage 120 by transfer tube or line 100. The transfer tube 100 is connected to the upstream stage outlet 36 and a downstream stage inlet 132. As seen in FIG. 5, the transfer tube 100 has an access port 101 selectively closed by a removable closure plug 102.

The downstream stage 120 includes a downstream stage compression tube 130, the downstream stage inlet 132, a downstream stage outlet and a downstream stage piston assembly 140.

The downstream stage compression tube 130 is fluidly connected to the downstream stage inlet 132 and the downstream stage outlet 136. The downstream stage piston assembly 140 is moveable within the downstream stage compression tube 130 in response to movement of the handle assembly 270.

The downstream stage piston assembly 140 includes a piston 150 and a piston rod 160 connecting the piston to the handle assembly 270. The piston 150 divides the downstream stage compression tube 130 into a second compression chamber 190 between the downstream stage inlet 132 and the piston 150, and a venting chamber 170 between the piston and an upper, as shown in FIGS. 1-5, (opposing) end of the downstream stage compression tube. As seen in FIG. 4, the downstream stage outlet 136 can be spaced from the sweep of the piston 150, such that a portion of the second compression chamber 190 can include a volume between the piston and the downstream stage outlet.

The downstream stage inlet 132 includes an inlet valve 134, such as check valve. The check valve 134 can be a simple gravity or spring actuated check valve, admitting compressed air from the first compression chamber 90 and precluding passage of air from the second compression chamber 190 as the volume of the second compression chamber decreases.

The venting chamber 170 is exposed or exposable to ambient pressure, such as though venting ports 173, which can include check valves for controlling the exit flow of air from the downstream stage 120. In one configuration, the venting ports 173 are located in an upper end of the piston rod 160, which is exposed to ambient pressure. As set forth below, a lower portion of the piston rod 160 includes venting ports 173 exposing the venting chamber 170 to the interior of the piston rod.

The piston 150 is moveable between a first position minimizing the volume of the second compression chamber 190 (such as adjacent the downstream stage inlet 132) and a second position maximizing the volume of the second compression chamber (such as adjacent an upper end of the downstream stage compression tube 130). Therefore, as the piston 150 moves between the first position and the second position, the volumes of the venting chamber 170 and the second compression chamber 190 vary in an inverse relationship.

As seen in FIGS. 4 and 5, the venting chamber 170 is an annular volume between an outside surface of the piston rod 150 and an inside surface of the compression tube 130. The piston rod 160 includes at least one and advantageously a plurality of venting apertures 173 for passing air from the venting chamber 170 to the interior of the piston rod 160.

As the interior of the piston rod 160 is fluidly connected to the venting ports 173, air can pass from the venting chamber 170 of the downstream stage 120 to ambient pressure.

The downstream stage outlet 136 includes a high pressure check valve 138 for passing compressed air from the second compression chamber 190 of the downstream stage 120 to an output line 260.

A pressure gauge 290 as known in the art can be in communication with the output line 260.

In one configuration, the volume of the first compression chamber 90 is between 1.25 to 2.75 times greater than the volume of the second compression chamber 190. In further configurations, the volume of the first compression chamber 90 is between 1.75 to 2.25 times and in additional configurations approximately 2 times greater than the volume of the second compression chamber 190.

The regulating valve 240 is located to selectively control the mass, or amount of compressed air passing from the upstream stage 20 to the downstream stage 120. Specifically, the regulating valve 240 controls the mass of compressed air passing from the first compression chamber 90 to the second compression chamber 190. By venting a portion of the compressed air generated by the first compression chamber 90 before such compressed air is introduced into the second compression chamber 190, the regulating valve 240 controls the mass of air transferred between the stages 20, 120.

The regulating valve 240 can be any of a variety of commercially available and known valves that can be adjusted or set to pass varying amounts or pressures of a compressed gas.

In one configuration, the regulating valve 240 is in fluid communication between the first compression chamber 90 and ambient pressure. As seen in FIG. 5, the regulating valve 240 includes at least one valve member 242 movable between an opening and a closed position. In the configuration of FIG. 5, a plurality of round valve members 242 are disposed in corresponding valve seats 244 and biased into the closed position by corresponding controllable springs or loads 246. Specifically, in one configuration, a control knob 250 is threadingly engaged relative to the spring 246 to selectively change the force exerted by the spring on the valve members 242.

By varying the amount of bias against the valve members 242, the regulating valve 240 can be adjusted to control the mass of compressed air passing from the first compression chamber 90 to the second compression chamber 190, through the selective passing of a portion of the mass of the air from the first stage 20 to ambient, prior to entering the second stage 120.

Although the regulating valve 240 is shown disposed adjacent the upstream stage outlet 36, it is understood, the regulating valve can be in any location in fluid communication with the compressed air generated in the first compression chamber 90, prior to the compressed air entering the second compression chamber 190.

The handle assembly 270 includes at least a handle 272 connected or linked to the piston rod 60 of the upstream stage 20 and the piston rod 160 of the downstream stage 120 for implementing movement of the respective piston within the respective compression tube.

The handle assembly 270 can include any of a variety of linkages interconnecting the handle 272 relative to the compression tubes and the pistons. For example, the handle assembly 270 can include a linkage system between a handle and a piston assembly as disclosed in U.S. Pat. No. 7,637,203, hereby expressly incorporated by reference.

By employing the transfer tube 100, the respective piston assemblies in the upstream stage 20 and the downstream stage 120 can simultaneously travel in the same direction with the handle assembly 270 to provide the desired pressurized air.

In one configuration, the transfer tube 100 can retain a sorbent cartridge 110 located such that pressurized air from the upstream stage 20 passes through the cartridge to be exposed to a retained sorbent 112.

The sorbent cartridge 110 includes a cartridge tube 111, the retained sorbent 112 and cooperatively engages sealing plugs 104. The cartridge tube 111 is generally cylindrical and sized to pass through the access port 101. In one configuration, the cartridge tube 111 is formed of a material that can withstand the pressurized gas passing from the upstream stage to the downstream stage. Thus, the cartridge tube 111 can be formed of metal, alloys or selected high strength plastics. Further, the cartridge tube 111 can be formed of a recyclable material such as thermoplastic or a thermoplastic elastomer.

Referring to FIGS. 4 and 5, the sealing plug 104 can be incorporated into an upstream end and a downstream end of the sorbent cartridge 110 to ensure passage of pressurized air from the upstream stage 20 to the downstream stage 120 through the sorbent cartridge and preclude passage leakage of pressurized air from the transfer tube 100 to the ambient environment. The sealing plug 104 includes at least one circumferential groove 105 retaining an O-ring seal or gland 106. As seen in the Figures, the sealing plug 104 can include two grooves 105 each with corresponding O-ring seal or gland 106. The sealing plug 104 further includes a through channel 107 for passing pressurized air through the sealing plug and into (or out of) the sorbent material 112 in the sorbent cartridge 110, wherein the through channel has an exposed port between the two seals of the respective sealing plug 104. The sorbent cartridge 110 (and the sealing plugs 104) thereby provide a flow path for the pressurized gas from the upstream stage to the downstream stage. The sealing plugs 104 can be formed of the same or a different material than the cartridge tube 111.

In an alternative configuration, one of the sorbent cartridge 110 and the transfer tube 100 includes at least one and advantageously two or more seals between an outside surface of the sorbent cartridge and an inside surface of the transfer tube. The seals are sufficient to prevent pressurized flow between the outside surface of the sorbent cartridge 110 and an inside surface of the transfer tube 100. Thus, flow of pressurized air passing through the transfer tube 100 is exposed to the sorbent material in the sorbent cartridge 110.

The media in the sorbent cartridge 110 can include moisture removing and retaining material such as desiccants including indicating desiccants as commercially available from Multisorb Technologies, Buffalo, N.Y. Thus, the sorbent cartridge 110 can include a translucent or transparent window for visually checking the status of an indicating desiccant.

The sorbent cartridge 110 can also include a particulate filter 116 at one or both an upstream or downstream end of the cartridge. A filter 118 at the downstream end of the sorbent cartridge 110 or transfer tube 100 can be selected to trap any sorbent material entrained in the flow. The filters 116, 118 can include metallic as well as felt or composite non-woven filters. The sorbent cartridge 110 (including sealing plugs 104 and filters 116, 118) is sized to pass through the access port 101 into the transfer tube 100, thereby permitting selective changing of the cartridge.

Thus, the sorbent cartridge 110 is provided in an inter-stage location in a multistage pump 10. The sorbent cartridge 110 receives compressed air having passed through at least one stage and exposes the compressed air to the sorbent before passing from the multistage pump, and advantageously before being subjected to high pressure compression.

It is further understood the sorbent material can be directly retained within the transfer tube 100, wherein depending on the specific sorbent material, filters such as 116, 118 can be located at the upstream and/or downstream end of the sorbent material in the transfer tube.

In operation, the handle assembly 270 starts in the down position with the piston 50 in the upstream stage 20 being adjacent the upstream stage inlet 32 (minimizing the volume of the accumulating chamber 70 and maximizing the volume of the first compression chamber 90) and the piston 150 in the downstream stage 120 being adjacent the downstream stage outlet 136 (minimizing the volume of the second compression chamber 190 and maximizing the value of the venting chamber 170).

Upon upward motion of the handle assembly 270, the piston rod 60, 160 in each of the upstream stage 20 and the downstream stage 120 is moved upward, thereby drawing the respective piston upward.

As the piston 50 in the upstream stage 20 moves upward, ambient air is drawn into the accumulating chamber 70 through the upstream stage inlet 32. The bypass valve 52 precludes flow between the accumulating chamber 70 and the first compression chamber 90. As the piston 50 in the upstream stage 20 moves upward, the air in the first compression chamber 90 is compressed and urged passed the regulating valve 240, through the transfer tube 100 (and sorbent cartridge 110, if employed), through the downstream stage inlet 132 and into the second compression chamber 190.

Further, as the piston 150 in the downstream stage 120 moves upward, any increase in pressure in the venting chamber 170 causes a flow out through the venting apertures 173 to ambient pressure. Thus, back pressure on the surface of piston 150 exposed to the venting chamber 170 in the downstream stage 120 is maintained substantially at ambient pressure.

In the configuration shown in the figures, as the volume of the second compression chamber 190 is approximately half the volume of the first compression chamber 90, the pressure of the transferred compressed air from the upstream stage 20 to the downstream stage 120 has approximately doubled.

As the handle assembly 270 is then pushed downward, the piston rod in each of the upstream stage 20 and the downstream stage 120 is moved downward, thereby pushing the respective piston downward.

Upon downward motion of the piston 50 in the upstream stage 20, the bypass valve 52 allows air in the accumulating chamber 70 to pass into the first compression chamber 90, thereby filling the first compression chamber with substantially ambient pressure air.

Upon downward motion of the piston 150 in the downstream stage 120, the downstream stage inlet valve 134 closes precluding flow back into the transfer tube 100. In addition, downward motion of the piston 150 in the downstream stage 120 compresses the compressed air in the second compression chamber 190.

Upon the compressed air in the second compression chamber 190 reaching a predetermined pressure, the compressed air opens the high pressure check valve 138 and passes the finally compressed air to the output line 260.

During the above operation, when the regulating valve 240 is in the closed position, all the mass of compressed air generated in the first compression chamber 90 passes from the first compression chamber, through the transfer tube 100 and into the second compression chamber 190.

Alternatively, the regulating valve 240 can be moved from the closed position to an opening position. That is, the closing force on the valve member(s) in the regulating valve 240 can be less than the force on the valve member 242 created by the maximum pressure generated in the first compression chamber 90. Thus, upon generation of sufficient pressure in the first compression chamber 90, the regulating valve 240 opens, thereby allowing some compressed air (mass) in (or from) the first compression chamber 90 to pass to the ambient environment. Therefore, less than the entire mass of air once resident in the first compression chamber 90 will pass to the second compression chamber 190. The result of decreased mass of air in the second compression chamber 190, in conjunction with the linkage of the handle assembly, is a reduced downward force on the handle 272 of the handle assembly 270 to minimize the volume of the second compression chamber. That is, the reduced mass of air in the second compression chamber 190 requires a reduced compressing force from the handle assembly 270 to reach the threshold of the high pressure check valve 138.

It is further contemplated the regulating valve 240 can be adjusted during or between strokes of the handle assembly and hence pistons. Thus, while the pressure in the second compression chamber 190 is relatively low (as compared to the target pressure), the regulating valve 240 can be closed to pass all the compressed gas from the upstream stage 20 to the downstream stage 120. Then, as the pressure increases in the downstream stage 120 (increasing the required force on the handle assembly), the regulating valve 240 can be adjusted to vent a portion of the compressed air in the upstream stage 20, thereby reducing the mass of gas to be compressed per cycle in the downstream stage 120. While, this process increases the total number of cycles of the handle assembly 270 to reach the desired pressure in the downstream stage 120, the required force on the handle assembly is reduced.

The ability to control the mass flow from the first compression chamber 90 to the second compression chamber 190 effectively varies the volume of the first compression chamber and thus varies the volume ratio of first compression chamber to the second compression chamber and therefore, the necessary force to minimize the volume of the second compression chamber. That is, as the volume ratio of first compression chamber 90 to the second compression chamber 190 tends towards 1, the force necessary to minimize the volume of the second compression chamber decreases (making the pump easier to actuate).

It is understood, as the required force to minimize the second compression chamber 190 decreases (due to the decreased mass transferred to the second compression chamber), the number of strokes necessary to provide a given mass of finally compressed air at the maximum pressure increases.

The following values are representative and not limiting of the present system. In one configuration, the first compression chamber 90 has a volume that is approximately twice the volume of the second compression chamber 190. However, by selectively setting the regulating valve 240 the structural 2:1 volume ratio of the compression chambers can be infinitely varied from 2:1 to 1.85:1, to 1.5:1 or even 1:1.

With the regulating valve 240 in the closed position, a pressure at the output of approximately 3,000 psi requires about 150 pounds of force on the handle assembly. By “opening” the regulating valve 240 to vent some of the mass of compressed air from passing into the second compression chamber 190, the pump 10 can provide 3,000 psi air with 85 to 90 pounds force on the handle assembly 270.

It is understood the reduced required force on the handle 272 is partly accomplished by the mechanical advantage of the upper linkages of the handle assembly 270. The peak pressure in the compression tube dictates the resulting force acting on the respective piston, which in the present configuration is constant since the cross sectional area of the piston does not change. The peak felt force on the handle 272 increases or decreases as a result of where the pressure builds relative to the piston/handle stroke. Thus, the load on the piston rod would be equal regardless of the mass transferred so long as there was adequate volume to achieve the desired high pressure, such as 3 ksi.

Thus, as seen in FIGS. 3-7, by virtue of the sealing plugs 104, the sorbent cartridge 110 can provide passage of compressed gas between the upstream stage and the downstream stage. spaced seals along the length of the cartridge. That is, the compressed gas from the upstream stage is introduced into the transfer tube by passing directly into the sorbent cartridge 110 through the sealing plug 104 between the seals.

With respect to the sorbent cartridge 110, upon a given number of cycles or time, the access port 101 can be opened and the sorbent cartridge removed, and replaced.

As used herein the term “upstream” refers to a direction or place from which a flow travels and the term “downstream” refers to a direction or place toward which a flow travels.

The invention has been described in detail with particular reference to a presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein. 

1. A multistage air pump comprising: (a) an upstream stage having a first compression chamber pressurizing a volume of a gas to a pressure above ambient pressure; (b) a downstream stage having a second compression chamber fluidly connected to the first compression chamber; and (c) a regulating valve for selectively venting a portion of the pressurized gas to reduce a mass of pressurized gas passing to the second compression chamber.
 2. The multistage air pump of claim 1, wherein the second compression chamber is partly defined by a downstream stage inlet, and the downstream stage inlet includes an inlet valve.
 3. The multistage air pump of claim 2, wherein the downstream stage inlet is formed by the inlet valve.
 4. The multistage air pump of claim 1, wherein the regulating valve precludes ambient air from passing through the regulating valve into the first compression chamber.
 5. The multistage air pump of claim 1, wherein the regulating valve is moveable between a closed position precluding pressurized gas from passing from the first compression chamber through the regulating valve to an ambient pressure and an opening position permitting at least a portion of pressurized gas to pass from the first compression chamber to ambient pressure.
 6. The multistage air pump of claim 1, further comprising a transfer tube intermediate the upstream stage and the downstream stage.
 7. The multistage air pump of claim 6, further comprising a sorbent cartridge in the transfer tube.
 8. The multistage air pump of claim 1, further comprising a sorbent cartridge fluidly intermediate the upstream stage and the downstream stage.
 9. The multistage air pump of claim 1, wherein the regulating valve is fluidly connected to the second compression chamber.
 10. A multistage air pump, comprising: (a) an upstream stage having an upstream stage inlet and an upstream stage outlet, the upstream stage increasing a pressure of a gas from the upstream stage inlet to the upstream stage outlet; (b) a downstream stage having a downstream stage inlet fluidly connected to the upstream stage outlet and a downstream stage outlet; and (c) a regulating valve in fluid communication with at least one of the upstream stage outlet and the downstream stage inlet, the regulating valve selectively passing pressurized gas prior to the downstream stage inlet to decrease a mass of pressurized gas passing through the downstream stage inlet.
 11. The multistage air pump of claim 10, wherein the regulating valve decreases a volume of pressurized gas passing through the downstream stage inlet.
 12. The multistage air pump of claim 10, wherein the regulating valve decreases a mass of pressurized gas passing through the downstream stage inlet.
 13. A method of operating a multistage air pump, the method comprising: (a) increasing a gas pressure in a first compression chamber of an upstream stage to a first pressure; and (b) selectively venting a portion of the pressurized gas prior to entering a second compression chamber in a downstream stage, the venting reducing a mass of pressurized gas transferred from the first compression chamber to the second compression chamber.
 14. The method of claim 13, wherein the venting occurs during each stroke of the pump.
 15. The method of claim 13, wherein the venting occurs through a regulating valve fluidly connected to the first compression chamber.
 16. The method of claim 13, wherein the pressurized gas vents from the first compression chamber.
 17. A multistage air pump comprising: (a) an upstream stage having an upstream stage piston assembly and a first compression chamber; (b) a downstream stage fluidly connected to the upstream compression chamber, the downstream stage having a downstream stage piston assembly and a second compression chamber; (b) a handle operably connected to the upstream stage piston assembly and the downstream stage piston assembly; and (c) a sorbent cartridge fluidly intermediate the upstream stage and the downstream stage.
 18. The multistage air pump of claim 17, wherein the sorbent cartridge is located to pass pressurized gas from the upstream compression chamber to the downstream compression chamber.
 19. The multistage air pump of claim 17, further comprising a regulating valve selectively venting a portion of pressurized gas from the first compression chamber to reduce a mass of pressurized gas passing to the second compression chamber.
 20. The multistage air pump of claim 17, further comprising a transfer tube fluidly intermediate the upstream stage and the downstream stage, wherein the transfer tube is sized to retain the sorbent cartridge. 